The science publishing world is a complex one, but the pendulum is currently swinging away from the paywalled mega-journals of the last decade to a more open model — but it can still be hard to find a full copy of an article you need on short notice. Unpaywall is a browser plug-in that identifies the paper you’re looking for, then checks whether it’s available for free anywhere on the web.

Install the plug-in in Firefox or Chrome, and when you arrive at a page summarizing or showing part of an article, a little lock icon appears telling you whether you can get it somewhere else for free. For instance, on this paper the icon is grey (it’s still only available behind the paywall), but here (also at Nature), it’s green. Clicking it brings me to a PDF version hosted at Arxiv.

Unpaywall, it should be noted right away, is mainly an interface for a tool called oaDOI, which collects and collates databases of open access journals and articles. To make sure their contemporaries have access to their work, researchers will often submit their paper to preprint repositories (like Arxiv) or host it on their own pages or university databases.

Both are developed by Impactstory, a nonprofit focused on open-access issues in science.

Of course, there might be minor changes to the title, formatting, file name and so on in the final version. The tools make allowances for this, working with DOI numbers when they can, but also doing soft matching between titles and authors.

And if a paper has five or six authors, whose page or lab will host it? It’s time-consuming and frequently fruitless to search, and I myself have more than once had to request a copy directly from the researchers. Accommodating nosy journalists isn’t their job! So Unpaywall will be an invaluable tool for me, at least.

Much like RECAP, which searches for legal documents you’re requesting or uploads them if they’re not elsewhere available, it’s a great way to leverage the web to improve access. And it’s less ethically troubling than the illegal but extremely practical paper piracy of Sci-Hub. Not every paper is going to be available somewhere, but a heck of a lot are.

Other tools are in development that use the oaDOI and other open-access databases for various purposes, notes Nature. As I said, the pendulum is swinging that direction, and Nature is one of the publishing giants that will need to get ahead of it.